pecan vs pecan tree

pecan and pecan tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
pecan	Yes	No	No	No
pecan tree	Yes	No	No	No

As nouns, pecan and pecan tree are synonyms defined as:

pecan and pecan tree: tree of southern United States and Mexico cultivated for its nuts

Other synonyms of pecan include Carya illinoensis, Carya illinoinsis.

pecan (noun)	pecan tree (noun)
smooth brown oval nut of south central United States	tree of southern United States and Mexico cultivated for its nuts
tree of southern United States and Mexico cultivated for its nuts
wood of a pecan tree